Apparatus for feeding fluent dry material

ABSTRACT

Apparatus for feeding fluent dry material comprising two conveyors, one positioned above the other, the upper conveyor being adapted to feed material to the lower conveyor, and the two conveyors having a common discharge. The upper conveyor is operable to feed material forward at a relatively high rate, first filling the lower conveyor, and then continuing to feed the material forward into the discharge. As the quantity of material fed approaches a quantity somewhat less than a desired quantity, the upper conveyor is stopped. Then the lower conveyor, which is adapted to feed the material at a relatively low controllable rate, is operated to deliver the material into the common discharge to bring the total amount delivered up to the desired quantity.

ARTICLE-HANDLING APPARATUS This invention is concerned with conveyorsystems, for conveying rodlike articles, particularly cigarettes andother similarly light articles (including for example cigarette filterrods), in stack formation on conveyors in relation to which the articleslie transversely. in particular this invention is con cerned with asensor for controlling the stack flow at a junction of two or morestacks to or from which the articles are carries by separate conveyors,though a sensor according to this invention may be used in othercircumstances in which a signal is required in relation to the height ofthe stack of articles beneath the sensor, for example while loadingcigarettes into a tray.

A conveyor system according to this invention includes two substantiallyhorizontal conveyors extending in opposite directions from ajunctionzone above which is arranged a sensor mechanism comprising two sensormembers which are arranged to rest on the articles in positions lyingrespectively approximately above the ends of the two conveyors, andincluding a conveyor speed-regulating mechanism which controls the speedof one of the conveyors and is coupled to each sensor member by alostmotion device so that the speed-regulating mechanism can be moved inone predetermined direction as a result of movement of either one of thesensor members while the other sensor member remains stationary.

In a preferred arrangement the predetermined direction in which eithersensor member can move the speed-regulating mechanism corresponds todownward movement of either of the sensor members. ln other words, thespeed-regulating mechanism always takes up a position determined bywhichever sensor member is in a lower position. The converse is howeverin principle possible.

Furthermore, a preferred arrangement is one in which the twosensormembers are pivoted about spaced axes parallel to the articles, and inwhich the sensor members extend towards one another and cross oneanother as viewed in a direction parallel to the articles. l

The parts of the plates resting on the articles are preferably shaped soas to have a convex underneath surface as viewed in the direction of thearticles.

Examples of arrangements according to'this invention are shown in theaccompanying drawings. In these drawings:

FIG. 1 is a side view of one arrangement;

FIG. 2 is a plan view; and

H6. 3 is a side view of a different arrangement.

The sensor shown in accompanying drawings consists of two sensor platesl and 11 which have downwardly convex portions 12 and 13 resting onahorizontal stack of cigarettes carried by two: band conveyors l4 and15. The Junction Zone" lies below the plates and 11. A single row ofcigarettes is fed upwards into the junction zone by two bands 17 and 18which return over small idler pulleys 19 and 20. The conveyors l4 andpass round further pulleys 21 and 22, and the horizontal surface onwhich the complete horizontal stack rests is completed by two smallbridgepieces 23 and 24.

It will be seen that the convex parts 12 and 12 of the plates 10 and 11lie on opposite sides of .a vertical plane passing through the singlerow of cigarettes 16, this plane being the vertical centerline'of the Tjunction. Moreover, the plates 10 and 11 and the conveyors l4 and 15form a symmetrical arrangement so that the function of the conveyors 14and 15 can be interchanged.

The plates 10 and 11 are secured respectively ,to spindles 25 and 26 bywhich they are pivotably mounted. As shown in FIG. 2, the two plates areslightly staggered laterally and each has two slots leaving three legs27, the arrangement being such that the legs of each plate can passthrough the slots in the other plate. In other words, the platesintennesh with one another.

Outside the cigarette flow channel, the spindles 25 and 26 carryrespectively two arms 28 and 29 which are connected by links 30 and 31to the arms 32 and 33 of a bellcrank secured to a spindle 34 of a rotaryspeed-regulatingmechanism 35 which controls the direetion of rotationand the speed of ,a motor driving the conveyor 15. Each link 30 or 31passes through a hole in the cooperating arm 32 or 33 and has end nutsso that it can transmit a pull from the arm 28 or 29 to the arm 32 or33, as the case may be, but not a push. In other words, there is alostmotion connection between each arm 28 or 29 and the arm 32 or 33 ofthe bellcrank. As a result of this lost-motion connection, the bellcrankposition is determined by whichever of the plates 12 or 13 is the lowerposition. The bellcrank is biased in an anticlockwise direction, forexample by the weight of the arm 32.

FIG. 1 shows the plates 12 and 13 in their lowest positions, while thehighest possible positions are shown in chain dotted lines, the limit ofupward movement being determined by stops 36 and 37. it is important tonote that the volume (in terms of the number of cigarettes) lyingbetween the uppermost and lowermost positions of the sensor plates issubstantial, i.e. the same order as the average volume of the junctionzone. This is significant as it means that the sensor also serves as auseful reservoir to allow for short term variations in the rates of feedto and from the junction zone.

Plates 38 and 39 cooperate with the ends of the pivoted plates 12 and 13to prevent the escape of cigarettes, and are appropriately slotted tointermesh with the sensor plates. As shown in H6. l,the plate 38 at itsllower end 38A extends horizontally for a short distance so as to serveas a top wall confining the upper surface of the stack of cigarettes fora short distance from the junction. The plate 39, on the other hand,merely curves upwards slightly to a point close to a band 50 whichserves as a top wall confining the upper surface of the stack in theother direction from the junction.

In one possible example, the conveyor band 14 continuously carries tothe left a stack of cigarettes delivered by the bands 17 and 18, whilethe conveyor 15 serves as part of a reservoir which receives cigarettes(i.e. with the conveyor 15 moving to the right) when the upward supplyof cigarettes 16 exceeds the rate of withdrawal of cigarettes by theconveyor 14; on the other hand, when the rate of withdrawal ofcigarettes by the conveyor 14 exceeds the rate of supply to the junctionby the bands 17 and 18, the conveyor 15 moves to the left so as todeliver cigarettes from. the reservoir. Further details of thisarrangement are described in British Pat. application Nos. 54034/68 and4l95/69. The sensor in this case may control the speed and direction ofmovement of the conveyor 1 5, while another sensor (which may be similarto the sensor shown in the drawings) may control the speed of theconveyor 14; for example, the far end of the conveyor 14 which is notshown may be at a further junction with an upward deliver similar tothat shown in FIG. 1.

An important advantage of a double plate sensor according to thisinvention is that each plate can be made particularly sensitive to adrop in the level of cigarettes caused by an excessive delivery awayfrom the junction by a conveyor beneath it or nearer to it. Consideringfor example a mode of operation in which, for the moment, the conveyor15 is stationary while the conveyor 14 is rotating at a speed whichexactly carries away the amount of cigarettes fed upwards by the bands17 and 18; if then the speed of the conveyor 14 where to increaseslightly, or if the rate of upward delivery of cigarettes by the bands17 and 18 were suddenly to decrease according to our observation thischange would be most quickly manifested by a drop in the level ofcigarettes at the end of the conveyor 14, that is to say adjacent to thestationary bridge piece 23 as a result a hollow would form in the uppersurface of the stack of cigarettes, and the convex part 12 of thepivoted plate 11 is so shaped (as nearly as possible) that it will sinksnugly into the hollow, thus rotating the spindle 34 of thespeed-regulating mechanism 35 in a clockwise direction which causes theconveyor 15 to start moving to the left at a speed such as to meet thedeficiency in the cigarette supply to the conveyor 14. If the doubleplate sensor were replaced by a single central sensor (i.e. lyingdirectly above the bands 17 and 18), the response would be slower as thelevel of cigarettes would take longer to fall away beneath such acentrally positioned sensor (and in a APPARATUS FOR FEEDING FLUENT DRYMATERIAL BACKGROUND OF THE INVENTION This invention relates to apparatusfor feeding fluent dry materials, and more particularly to suchapparatus for use in bulk material handling.

The invention is particularly useful in dry batching systems such asemployed in the manufacture of animal feed. In such systems, differentdry fluent materials are fed by conveyors from a plurality of storagehoppers to a weighing station for proportioning of the materials forbatching.

Screw conveyors, as heretofore used in such systems, have had certainobjectionable characteristics. For example, in prior systems utilizingscrew conveyors, either accuracy or flow rate had to be compromised.Systems in which the quantity must be proportioned accurately requiredconveyors with relatively low feed rates to provide the control requiredfor greater accuracy, but such a system required additional time to feeda given quantity of material, thus reducing the production rate.Conversely, use of conveyors with relatively high feed rates for feedingthe material rapidly caused difficulty in accurate control of thequantity of material fed.

Dry fluent material, when conveyed, tends to build up adjacent theflights of the conveyor so that the relationship of the flights to thedischarge determines, to some extent, the amount of material which willcontinue to flow after the conveyor has stopped. The angle of repose,which is affected by moisture content (a day-to-day variable), alsoaffects the amount of material which will continue to flow once theconveyor is stopped. The fluidity of the material, which is affected bythe moisture content, affects the power required to move the materialand thus the time required for the conveyor to stop. These variablespreclude predetermining with any degree of accuracy the point at whichthe conveyor can be stopped accurately to deliver a given quantity ofmaterial.

Accurate delivery of a given quantity of material is not only necessaryfor a high-quality product but also has economic advantages. In orderthat no less than the desired quantity be delivered, inaccuracies arenormally on the high side, producing overages for which the customerdoes not pay. While a sin gle overage is insignificant, the aggregateover a longterm operation is significant and may amount to substantiallost income.

SUMMARY OF THE INVENTION Accordingly, among the several objects of thisinvention may be noted the provision of apparatus for feeding fluent drymaterial, particularly useful for batching operations as abovedescribed, adapted for operation rapidly to deliver accurately measuredquantities of the material; the provision of such apparatus adapted formanufacture as original equipment or as a modification of existingequipment; and the provision of such apparatus which is economical tomanufacture and reliable and easy to use.

In general, apparatus made in accordance with this invention comprisesan upper conveyor for the material and a lower conveyor for the materiallocated below the upper conveyor. The upper conveyor is adapted to feedthe material forward to a point of discharge at a relatively highvolumetric rate and has an outlet for discharge of material into thelower conveyor rearward of said point of discharge. The lower conveyoris adapted to feed material received from the upper conveyor forward toa point of discharge at a relatively low volumetric rate. Thearrangement is such that the upper conveyor may be operated rapidly tofeed out an amount somewhat less than said quantity, and the lowerconveyor may then be operated to feed out the remainder for accuratelycontrolled feeding of said quantity. Other objects and features will bein part apparent and in part pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a vertical section of abatch system showing two conveyor units for feeding fluent dry material;

FIG. 2 is an enlarged vertical section on line 2-2 of FIG. 1;

FIG. 3 is an enlarged horizontal section on line 3-3 of FIG. 1, showingan opening between the upper and lower conveyors ofone of the conveyorunits;

FIG. 3A is a view similar to FIG. 3 showing a modification; and

FIG. 4 is a vertical section showing a modification.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. I of thedrawings, there is indicated at 1A a first conveyor unit and at 18 asecond conveyor unit for feeding dry fluent material to a weightingstation 3 (e.g., a scale having a hopper for receiving the material).The first conveyor unit 1A comprises an upper conveyor 5 for thematerial and a lower conveyor 7 for the material located below the upperconveyor. The upper conveyor is adapted to feed the material forward (tothe right, as illustrated at IA) to a point of discharge above theweighing station at a relatively high volumetric rate and has an outlet9 for discharge of the material into the lower conveyor 7 rearward ofthe point of discharge. The lower conveyor 7 is adapted to feed thematerial received from the upper conveyor 5 forward (to the right, asillustrated at IA) to a point of discharge above the weighing station ata relatively low volumetric rate. The arrangement is such that the upperconveyor 5 may be operated rapidly to feed out an amount of materialsomewhat less than the desired quantity and then the lower conveyor 7may be operated to feed out the remainder for accurately controlledfeeding of said quantity.

The upper conveyor 5 of unit IA comprises an elongate trough 11 havingan end wall 13 at its discharge end (its right end, as illustrated).Outlet 9 is constituted by an elongate slot in the bottom of trough 11extending rearward for some distance from the discharge end of thetrough. Extending endwise in the trough is a drag conveyor generallydesignated 15, comprising a series of flights 17 in the form of paddleson an endless chain I9. The flights conform to the shape of the bottomportion of the trough. At D1 is indicated means for driving the dragconveyor at relatively high. speed in the direction for travel of theflights on the lower reach of the chain toward the discharge end of thetrough.

The lower conveyor 7 comprises a trough 23, having a lengthcorresponding to the length of the slot 9 and a width corresponding tothe width of slot 9, mounted underneath the trough II at the dischargeend of the latter by welding or otherwise suitably securing its upperedges to the bottom of trough I1. At the discharge end of trough 23 (itsright end, as illustrated) is a downwardly directed discharge chute 25for delivering material to the weighing station. Wall 13 has a downwardextension constituting the discharge end of the lower conveyor 7.Extending endwise in trough 23 is a screw conveyor generally designatedat 27, comprising a shaft 29 having radial flights 31 which form acontinuous lengthwise spiral extending along the shaft. At D2 isindicated a means for driving the screw conveyor 27 in a direction oftravel which causes the material to feed toward the discharge end of thetrough 23. The screw conveyor 27 and the bottom of the trough 23 areangled with respect to the drag conveyor I5 and the trough 19 so thatthe axes of the two conveyors form an acute angle having an apexadjacent the discharge.

The screw conveyor shaft 29 may have its discharge end journaled in abearing 32 fastened to end wall 13. Having the bearing 32 mounted on theoutside of the end wall 13 is desirable if the material conveyed ishighly abrasive. If not, the bearing may be positioned within thedischarge chute as indicated at 320 in FIG. 3A by having the trough 23extend into the discharge chute and provided with an end wall 33attached thereto for mounting the bearing 32a. The bottom part of thetrough 23 is cutaway within the discharge chute 25, providing a bottomdischarge 35 for the lower conveyor. Mounting the bearing 32 within thedischarge chute may reduce installation cost, particularly where anexisting conveyor is being modified to incorporate this invention.

The second conveyor unit illustrated generally at 1B is similar to thefirst conveyor unit LA hereinbefore described except that it has a screwconveyor generally indicated at 37 extending endwise in the trough 11,instead of the drag conveyor 15. The drag type of conveyor is preferredfor new installations because it has a higher delivery capability thanthe same size screw conveyor. However, the majority of existing batchingsystems employ screw conveyors, so that existing systems may be modifiedto includemany of the advantages of this invention by installing thelower conveyor below an existing screw conveyor, as illustratedgenerally at 18.

HO. 4 illustrates an alternate arrangement wherein the upper conveyor isinstalled in an inclined position with respect to the horizontal so thatthe conveyor ascends in the direction of the flow. When so installed,the incline may provide sufiicient angular displacement for the lowerconveyor 70 so that the axes of the two conveyors may be generallyparallel.

The upper and lower conveyor drives, indicated generally at D1 and D2,respectively, operate in an alternating cycle. Starting the upperconveyor drive Dl begins the cycle by feeding the fluent dry materialforward at a relatively high rate, filling the lower conveyor 7. Havingfilled the lower conveyor, the upper conveyor 5 continues feeding thematerial forward through the discharge chute 25 into the weighingstation hopper 3. As the quantity of material fed approaches an amountsomewhat less than the desired quantity, the upper conveyor drive D1 isstopped. Starting the lower conveyor drive D2 feeds additional materialforward through the discharge chute 25 into said hopper 3 at arelatively low controllable rate. When the quantity of material fedreaches the desired quantity, the lower conveyor drive D2 is stopped.Additional material may be fed by jogging the lower conveyor. Havingobtained the desired a quantity of material, the cycle is ready to berepeated.

A quantity of material sufficiently short of the desired quantity atwhich the upper conveyor 5 should be stopped is generally the amount ofmaterial held in the upper conveyor 5 directly above the outlet 9, plusone-half of the material held in the lower conveyor 7. Feeding saidquantity of material via the lower conveyor causes the materialremaining in the lower conveyor to vibrate down the angled trough 23rather than slide into the discharge chute. Material remaining in theupper conveyor will vibrate in the rearward end of the lower conveyor.Operating the lower conveyor so as to leave it approximately one-halffull insures the availability of sufficient material to deliver thedesired quantity and provides flexibility in the operation of theequipment.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

lclaim:

1. Apparatus for feeding out a quantity of fluent dry materialcomprising an upper conveyor for the material and a lower conveyor forthe material located below the upper conveyor, the upper conveyorcomprising a trough having conveyor means extending lengthwise thereofadapted to feed material in the said upper conveyor trough in thedirection toward one end thereof constituting its forward end at arelatively high volumetric rate, said upper conveyor trough having anelongate bottom outlet at its forward end for bottom discharge of thematerial, the lower conveyor comprising a trough extending under saidelongate bottom outlet of the upper conveyor trough for receivingmaterial therefrom, conveyor means extending lengthwise of the lowerconveyor trough adapted to feed material in said direction along thelower trough toward one end thereof constituting its forward end at arelatively low volumetric rate, said lower conveyor trough having abottom outlet at its forward end, a forward portion of the bottom outletof the upper conveyor trough and the bottom outlet of the lower conveyortrough being in direct communication with a common delivery station fordirect gravity flow of the material to said delivery station from eachconveyor trough, the rearward portion of the bottom outlet of the upperconveyor through being in communication with the lower conveyor troughrearward of the bottom outlet of the latter, whereby the upper conveyormay be operated to supply the lower conveyor trough and then rapidly tofeed out an amount of material somewhat less than said quantity directlyfrom the upper conveyor outlet to the delivery station with the lowerconveyor means out of operation, and the lower conveyor means may thenbe operated to feed out the remainder for accurately controlled feedingof said quantity.

2. Apparatus as set forth in claim I wherein the forward portion of thebottom outlet of the upper conveyor trough is directly above the bottomoutlet of the lower conveyor trough.

3. Apparatus as set forth in claim 1 wherein each of the upper and lowerconveyors is a screw conveyor.

4. Apparatus as set forth in claim 1 wherein the upper conveyor is adrag conveyor and the lower conveyor is a screw conveyor.

5. Apparatus as set forth in claim 1 having a discharge chute extendingdown from the bottom outlet of the upper conveyor trough and the forwardend of the lower conveyor trough ex tends partially into said chute.

6. Apparatus as set forth in claim 1 wherein the axes of both conveyormeans are generally parallel.

7. Apparatus as set forth in claim 1 wherein the axis of the lowerconveyor is angled with respect to the horizontal so that it ascends inthe direction of flow.

8. Apparatus as set forth in claim 1 having separate drive means foreach conveyor.

1. Apparatus for feeding out a quantity of fluent dry materialcomprising an upper conveyor for the material and a lower conveyor forthe material located below the upper conveyor, the upper conveyorcomprising a trough having conveyor means extending lengthwise thereofadapted to feed material in the said upper conveyor trough in thedirection toward one end thereof constituting its forward end at arelatively high volumetric rate, said upper conveyor trough having anelongate bottom outlet at its forward end for bottom discharge of thematerial, the lower conveyor comprising a trough extending under saidelongate bottom outlet of the upper conveyor trough for receivingmaterial therefrom, conveyor means extending lengthwise of the lowerconveyor trough adapted to feed material in said direction along thelower trough toward one end thereof constituting its forward end at arelatively low volumetric rate, said lower conveyor trough having abottom outlet at its forward end, a forward portion of the bottom outletof the upper conveyor trough and the bottom outlet of the lower conveyortrough being in direct communication with a common delivery station fordirect gravity flow of the material to said delivery station from eachconveyor trough, the rearward portion of the bottom outlet of the upperconveyor through being in communication with the lower conveyor troughrearward of the bottom outlet of the latter, whereby the upper conveyormay be operated to supply the lower conveyor trough and then rapidly tofeed out an amount of material somewhat less than said quantity directlyfrom the upper conveyor outlet to the delivery station with the lowerconveyor means out of operation, and the lower conveyor means may thenbe operated to feed out the remainder for accurately controlled feedingof said quantity.
 2. Apparatus as set forth in claim 1 wherein theforward portion of the bottom outlet of the upper conveyor trough isdirectly above the bottom outlet of the lower conveyor trough. 3.Apparatus as set forth in claim 1 wherein each of the upper and lowerconveyors is a screw conveyor.
 4. Apparatus as set forth in claim 1wherein the upper conveyor is a drag conveyor and the lower conveyor isa screw conveyor.
 5. Apparatus as set forth in claim 1 having adischarge chute extending down from the bottom outlet of the upperconveyor trough and the forward end of the lower conveyor trough extendspartially into said chute.
 6. Apparatus as set forth in claim 1 whereinthe axes of both conveyor means are generally parallel.
 7. Apparatus asset forth in claim 1 wherein the axis of the lower conveyor is angledwith respect to the horizontal so that it ascends in the direction offlow.
 8. Apparatus as set forth in claim 1 having separate drive meansfor each conveyor.